Pressurized dispensers for dispensing products utilizing a pressure transfer fluid

ABSTRACT

Reusable pressurized containers are disclosed for dispensing fluids from the container without release of the pressurized propellant to the surrounding environment. The propellant is contained in a sealed, flexible compartment positioned within the container as a mixture of gas and liquid under pressure in equilibrium at the temperature of the container. A pressure transfer liquid, such as water or compressed air, is used to liquefy the propellant in the compartment. The pressure transfer fluid also contacts the fluid or semi-solid to be dispensed and exerts pressure thereon to force the fluid to be dispensed out of the container. The liquefied propellant, as it vaporizes, maintains the pressure against the pressure transfer fluid essentially constant. The propellant in the flexible compartment is preferably a mixture of a liquefiable propellant gas or blend thereof and a non-liquefiable inert gas such as nitrogen or helium.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation-in-part of application Ser. No. 775,098, filedMar. 7, 1977, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to reusable pressurized containers for dispensingfluids without release of the liquefiable propellant used to dispensethe fluid to the surrounding atmosphere, to a method of making suchcontainers and to fluid reservoir systems employing a pressurizedliquefiable propellant.

2. Description of the Prior Art

Dispensing containers are widely used to dispense a myriad of products.Conventional pressurized dispensers generally use a propellant insolution with the product to be dispensed which is usually dischargedalong with the product into the atmosphere and which evaporatesinstantly upon discharge, helping break the product into a fine mist.The propellants commonly used include halogenated hydrocarbons, such asdifluorodichloromethane and dichlorotetrafluoroethane, and aliphatichydrocarbons, such as propane, isobutane, n-butane and mixtures thereof.

Recent concern has been expressed by scientists about the effects ofdischarge of fluorocarbon propellants into the atmosphere where theyaccumulate in the upper atmosphere and cause possible depletion of theozone layer enveloping the earth. Such concern has resulted inregulations to curtail the use of such propellants. Hydrocarbonpropellants such as propane, isobutane, butane and others, while notcreating an environmental problem, pose a safety hazard during storageand transportation because of their combustability, particularly whenthe container is discarded when not completely empty.

It is expected that free discharge of fluorocarbons into the atmospherewill be banned world-wide in the near future. Except for personalproducts and some food products, most of the users of fluorocarbonpropellants are expected to switch to hydrocarbon propellants. Shouldthis switchover take place, annual consumption of propane and isobutaneas propellants would increase from 100,000,000 pounds in 1971 to morethan 1,000,000,000 pounds in the near future, equivalent to about 24billion cu. ft. of natural gas at atmospheric pressure in the UnitedStates alone. This is a significant amount of fuel on an annual basiswhich could be better used to supply factories and provide employment.At the same time, probable safety hazards from the use of morehydrocarbon-filled aerosol cans will increase many times as fluorocarbonuse will likely be phased out in blending with hydrocarbon propellantsto reduce their flammability as a flame suppressant. With the containersdescribed herein, the total consumption of hydrocarbons could be a verysmall fraction of one percent of that used at present.

From the standpoint of (1) environmental protection of the ozone layer,(2) conservation of fuel energy, and (3) safety for the consumer and thepublic, the containers described herein are a solution to a seriousproblem.

Dispensers such as those disclosed in U.S. Pat. Nos. 3,460,714;3,578,210; 3,815,793; and 3,858,764, release the propellant into theatmosphere with the product to be dispensed.

U.S. Pat. No. 3,417,901 describes a reusable pressurized dispenserwherein a propellant which can be liquefied in a home refrigerator andwhich boils below operating temperature, is sealed in a flexiblecontainer in contact with the material to be dispensed. The propellant,when warmed to ambient temperature, forces the material to be dispensedout of the container. The container is refilled by cooling the containerto liquefy the propellant and then opening the container to add morematerial to be dispensed.

U.S. Pat. No. 2,930,513 describes a pressurized liquid dispenseremploying a compressed air propellant.

U.S. Pat. No. 3,233,791 utilizes a propellant operated gel piston whichis prone to leakage with release of the propellant to the atmosphere asthe product is dispensed.

U.S. Pat. No. 3,659,395 utilizes a closed cell foam material within acontainer. Propellant is injected into the container under pressurewhich diffuses through the walls of the foam into the foam cells. Theproduct to be dispensed is then injected under pressure into thecontainer. The propellant is not sealed but is released as the productis dispensed.

There remains a need for a pressurized dispenser which can be reusedrepeatedly without release of the propellant to the atmosphere which canbe manufactured economically.

Pressurized fluid reservoir systems currently used in the industry are,in some instances, of inadequate holding capacity for the same size unitand are not constant pressure systems.

SUMMARY OF THE INVENTION

This invention is directed to pressurized power systems for fluids,including reusable pressurized containers for dispensing fluids withoutrelease of the pressurized propellant within the container to thesurrounding environment, method of making such and pressurized fluidreservoir systems including means for maintaining the fluid pressuresubstantially constant. With respect to pressurized containers, acontainer having a valved outlet holding the product to be dispensedcontains a permanently sealed compartment having a propellant gasimpermeable, flexible wall holding a pressurized, liquefiable propellantor mixture of liquefiable propellant and non-liquefiable gas. Theliquefiable propellant is generally a mixture of gas and liquid at theuse temperature of the container when the container is not completelyempty of product. The propellant is liquefiable under the influence oftemperature, pressure or both. The container may also be designed toaccommodate a pressurized transfer fluid (liquid or non-propellant gas),which contacts both the flexible wall holding the propellant and theproduct to be dispensed directly or indirectly, the pressurized transferfluid transmitting sufficient pressure from the propellant to theproduct to be dispensed to force the product out of the containerthrough the valved outlet.

The pressurized fluid reservoir systems described herein comprise ahousing having an opening for receiving the pressurized fluid. Apermanently sealed compartment having a flexible wall is positionedwithin the housing and holds a liquefiable propellant gas, blendthereof, or a mixture of a liquefiable propellant gas or blend thereofand a non-liquefiable gas. The flexible wall separates the propellantand pressurized fluid.

It is a primary object of this invention to provide a pressurizeddispenser for dispensing products without release of the propellant tothe surrounding atmosphere.

It is another object of this invention to provide a fluid systemincluding a fluid reservoir and a compartment within the reservoirenclosing a liquefiable propellant gas, blend thereof, or a mixture of aliquefiable propellant gas and non-liquefiable gas at the usetemperature of the fluid system, the compartment having a flexible wallwhich is impermeable to the liquefiable propellant enclosed therein.

It is a further object of this invention to provide a method and meansof damping pressure pulsations in a fluid system.

It is a further object of this invention to provide a method and meansof maintaining and stabilizing the pressure within a fluid system.

It is a further object of this invention to provide a method and meansof compensating for fluid pressure loss or fluid loss in a fluid system.

It is a further object to provide a method of dispensing fluids from acontainer by enclosing a mixture of gases within a compartment having aflexible wall in contact with the fluid to be dispensed, the mixture ofgases including at least one liquefiable propellant gas and at least oneother non-liquefiable gas.

It is a further object of this invention to provide a pressurizeddispenser wherein the liquefiable propellant can be used repeatedly.

It is a further object of this invention to provide a pressurizeddispenser wherein the liquefiable propellant is sealed in a compartmenthaving a flexible, wall positioned in a separate container from theproduct to be dispensed by the liquefiable propellant.

It is a further object of this invention to provide a pressurizeddispenser wherein pressure for dispensing the product is transferred tothe product through a liquid or gas pressure transfer fluid.

It is a further object of this invention to provide a pressurizeddispenser wherein pressure for dispensing the product by the propellantis transferred to the product through a liquid or gas pressure transferfluid and wherein the liquefiable propellant is reusable by liquefactionof the propellant through pressure exerted thereon by the pressuretransfer fluid. For high pressure systems, the propellant may be cooledto a level where the available pressure through the pressure transferfluid is sufficient to liquefy the propellant.

It is a further object of this invention to provide a method of making apressurized dispenser employing a cellular foam material containing aliquefiable propellant gas.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of a pressurizeddispenser embodying the invention hereof;

FIG. 2 is a vertical cross section of one embodiment of a pressurizeddispenser having a top portion containing the product to be dispensedand a separate lower portion containing the liquefiable propellant and apressurized transfer fluid;

FIG. 3 is a vertical cross section of an alternative embodiment of theupper portion of FIG. 2;

FIG. 4 is a vertical cross section of a conventional Sepro-can containerwhich may be used in conjunction with the lower portion of FIG. 2;

FIG. 5 is a vertical cross section of an embodiment of the inventionwherein the product to be dispensed is contained in the lower containerand the liquefiable propellant and pressure transfer fluid are containedin the upper container;

FIG. 6 is a vertical cross section of a pressurized dispenser whereinthe product to be dispensed, the liquefiable propellant and pressurizedtransfer fluid are contained in a single, integral container;

FIG. 7 is a vertical cross section of an embodiment of the inventionlike FIG. 6;

FIG. 8 is a vertical cross section of one means of providing compressedair to a container as the pressurized transfer fluid;

FIG. 9 is a side elevational view of one means for connecting thecontainer holding the pressurized transfer fluid to a source of transferfluid under pressure;

FIG. 10 is a vertical cross section of a pressurized dispenser for paintemploying the inventive concept described herein;

FIG. 11 is a vertical cross section of a pressurized dispenser utilizinga flexible, expandable, multi-cellular material within a container, thecellular material holding a liquefiable propellant, or a blend ofliquefiable propellants, or a mixture of a liquefiable propellant orblend thereof and a non-liquefiable gas at the use temperature range ofthe dispenser; and

FIG. 12 is a vertical cross section of a pressurized fluid systemwherein a flexible, bladder is positioned within a fluid reservoirhousing, the bladder containing a liquefiable propellant, blend ofliquefiable propellants or a mixture of a liquefiable propellant orblend thereof and a non-liquefiable gas at the use temperature range ofthe fluid system;

FIGS. 13 and 14 are comparative pressure/volume graphs for a fluidsystem of the type shown in FIG. 12. FIG. 13 illustrates a systemwherein the bladder or foam material is filled with a non-liquefiablegas. FIG. 14 illustrates a system wherein the bladder or foam materialis filled with a mixture of a liquefiable propellant gas or blendthereof and non-liquefiable gas.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

"Liquefiable propellant" used herein means a compound or mixture ofcompounds having a boiling point or boiling range such that the vaporpressure of the compound or mixture of compounds at the use temperatureor temperature range is equal to the pressure exerted by the propellantwhich is wanted.

"Non-liquefiable gas" as used herein means a compound or mixture ofcompounds compatible with and inert with respect to the liquefiablepropellant and having a boiling point or boiling range sufficientlydifferent from that of the liquefiable propellant that it is notliquefiable at the temperatures and/or pressures which the dispenser orfluid system is to be operated.

FIG. 1 shows a container which may be separated into an upper container10 and a lower container 20, the upper container having a fingeractuator 16 for delivery of the material to be dispensed throughdispensing nozzle 15. Different embodiments of the upper container areillustrated by FIGS. 2, 3, 4 and 5. In each of these the liquefiablepropellant, or mixture of liquefiable propellant and non-liquefiable gasat the desired operating temperature range of the dispenser, isliquefied under the influence of pressure, temperature or both and issealed in a compartment having a flexible wall which is not permeable tothe liquefiable propellant gas. A pressure transfer fluid, such aswater, compressed air or other inert gas such as carbon dioxide, may beused to liquefy the propellant in the compartment. The pressure transferfluid is in contact with the flexible wall of the compartment holdingthe propellant so that the pressure exerted by the pressure transferfluid on the propellant in the compartment liquefies the propellant. Thepropellant in the compartment, after injection of the pressure transferliquid, exerts a constant and sufficient pressure against the pressuretransfer fluid in contact with the product to be dispensed to force theproduct out through the valved outlet of the container when the valve isopened.

Referring specifically to FIG. 2 the upper container 10 has a productchamber 12 which includes a dip tube 13 extending downwardly to thebottom of the container from valve 14 which controls the flow of theproduct 33 to be dispensed from dispensing nozzle 15 by the fingeractuator 16. The lower wall 17 of the container includes an openingsurrounded by an annular, internally threaded projection 18 and may havea conventional one-way, spring-loaded valve 19 therein. The valve 19 maybe of the type used for tire tubes, although other type valves may beused. In many applications, valve 19 may be omitted. A tube 11 may besecured over the valve 19 in the lower container wall 17 for someapplications. The tube 11 extends upwardly from the opening in lowerwall 17 to near the top of the container 10.

The lower container 20 includes side walls 21, top wall 22 and bottomwall 23. An annular, externally threaded projection 24, surrounding anopening 24a in the top wall, has a valve 25 therein of the same type asvalve 19. A flexible bag 26 is clamped around the opening 24a in the topwall to form a transfer fluid compartment 27 holding the pressuretransfer fluid 27a. A propellant chamber 28 between the flexible bag 26and the walls 21, 22 and 23 of the container holds a liquefiablepropellant 28a. The propellant is charged into the container through aninlet opening 29 sealed with a plug 29a of resilient material.

The locking system for securing the lower container 20 holding thepressure tranfer fluid 27a and propellant 28a to the upper container 10may be of several types, all known and obvious to one skilled in theart. The means for clamping the flexible bag 26 around the opening 24ain the top wall 22 of lower container 20 may be by means other than asillustrated. For example, an annular projection extending from the lowerend of projection 24 may be fitted with an annular detent and a ringused to clamp the flexible bag 26 around the projection 24. Other waysof sealing the bag may also be used. The bag holding the pressuretransfer fluid may be made of any convenient material provided it issubstantially impermeable to the propellant used, is sufficientlyflexible for the purposes described and is compatible with the pressuretransfer fluid and propellant.

Alternatively, the flexible bag 26 may be secured around the inletopening 29 to receive and contain the propellant 28a, and the pressuretransfer fluid 27a introduced through valved 25.

After manufacture of the lower container 20 an appropriate amount ofpropellant 28a is injected into the propellant chamber 28 through theinlet opening 29 and the inlet opening sealed with a plug 29a. With theembodiment shown in FIG. 2 compressed air, carbon dioxide or other inertgas not environmentally detrimental if released to the atmosphere, isused as the pressure transfer fluid 27a. The source of compressed airmay be from a service station air hose, a portable compressor or by useof the device shown in FIG. 8 using water to compress the air, or otherknown gas pressure storage means.

Using an appropriate fitting, compressed air or other gas is introducedinto the transfer fluid compartment 27 through the valve 25, thecompressed gas exerting sufficient pressure on the propellant 28a in thepropellant chamber 28 through the wall of flexible bag 26 to liquefy aportion or substantially all of the propellant 28a in compartment 28.The valve 25 may be a spring-loaded valve which closes to prevent lossof the air pressure from the transfer fluid chamber 27 when filling iscomplete. The upper container 10, filled with the product 33 to bedispensed, is then connected to the lower container 20 by connecting thetwo containers together as illustrated. The annular, internally threadedprojection 18 mates with the annular, externally threaded projection 24as illustrated in FIG. 2. When the upper and lower containers areconnected the pins of the respective valves 19 and 25 contact and openeach other to permit the pressurized transfer fluid 27a (in thisinstance gas) to enter the product chamber 12 of the upper containerthrough tube 11 and pressurize the product 33 therein. If valve 19 isnot provided, a stationary pin must be provided in its place to open thevalve 25 when the upper and lower containers are connected. When thevalve 14 of the container 10 is depressed the pressure above the product33 forces the product out through the valve and nozzle 15. Thepropellant 28a in the propellant chamber 28 exerts a constant pressureon the pressure transfer fluid 27a contained in the compartment 27which, in turn, exerts a constant pressure on the product 33 to bedispensed so that sufficient pressure is available to uniformlydischarge all of the product 33 from the container 10. As the product 33is dispensed, additional liquefied propellant vaporizes to maintain thepressure in the chamber 28 substantially constant. When the product 33to be dispensed is exhausted the upper container 10 is disconnected fromthe lower container 20 and may be discarded or refilled. The lowercontainer 20 may be reused by repressuring the container with a suitablegaseous pressure transfer fluid. Flexible, cellular material containingliquefiable propellant such as the one shown in FIG. 11 and describedlater may be substituted for propellant chamber 28 and the flexible bag26.

FIG. 3 illustrates a modified form of upper container 10 in which theproduct 33 to be dispensed is contained in a flexible bag 30, the bagclamped at its upper ends around the valve 14 of the container 10. Thematerial for the flexible bag 30, in this instance, need not beimpermeable to the propellant gas since it never comes into contact withthe propellant 28a. A dip tube 31, which may not be needed for someapplications, extends downwardly toward the bottom of the bag from itsconnection to the valve 14 controlling flow of the product to bedispensed from dispensing nozzle 15 on depression of finger actuator 16.This container also has a valved lower outlet similar to that describedwith regard to the upper container 10 of FIG. 2. The outlet may not needto be valved for many applications. A lower container 20 of the typedescribed with reference to FIG. 2 may be used in conjunction with thecontainer illustrated in FIG. 3. The pressure transfer fluid 27a usedwith the upper container 10 of FIG. 3 may be either a compressed gas,such as compressed air or carbon dioxide or a liquid such as water. Whenusing water, for example, transfer fluid compartment 27 of the lowercontainer 20 is filled with water under pressure, such pressuregenerally ranging from 5 to 80 psi or more from a convenient tap watersource. The pressure exerted by the water on the propellant 28a in thepropellant chamber 28 causes liquefaction of some or all of thepropellant therein. If available water pressure is insufficient toliquefy the propellant 28a, the propellant may be cooled to allow alower water pressure to liquefy the propellant. When the lower container10 is connected to the upper container as described with reference toFIG. 2, the water under pressure flows into chamber 32 of the uppercontainer 10 of FIG. 3 surrounding the flexible bag 30 and exertspressure on the product 33 so that, on depression of the finger actuator16 to open valve 14 the product is forced out through the dispensingnozzle 15. The propellant 28a in propellant chamber 28 exerts asubstantially constant pressure on the water in transfer fluidcompartment 27, this pressure being efficiently transmitted by the waterto the product 33 contained in the flexible bag 30.

FIG. 4 illustrates an upper container 10 similar to the "Sepro" canmanufactured by Continental Can Co. utilizing an accordion-like,flexible compartment 34 holding the product to be dispensed. When thecontainer 10 of FIG. 4 is connected to the lower container 20 of FIG. 2as previously described, the pressure transfer fluid 27a in transferfluid compartment 27 enters chamber 32 and exerts pressure against theflexible compartment 34 to dispense the product 33. When the valve 14 isopened the product 33 is forced out through the dispensing nozzle 15.The embodiment illustrated in FIG. 4 is useful for dispensing some lowviscosity products at low pressures or viscous products at highpressures, such as cheese spreads, syrup, honey, etc.

Water is a preferred transfer fluid because it is, for all practicalpurposes, incompressible, and transmits pressure efficiently; however,other liquids may be used as long as they are compatible with theoverall system.

If desired, means may be included with the valves of the variousembodiments to produce a fine spray. For example, the orifice leadingfrom the valve 14 of FIGS. 2 and 3 may include mechanical means such asswirl chamber to break up the material being dispensed. Alternatively, avapor tap orifice inside the container, a tapered orifice, an air taporifice on the spray head outside the can or dissolved gas such ascarbon dioxide in the product to be dispensed may be employed.

In contrast to the use of pressure, cooling may be used to condense thepropellant 28a in compartment 28 of the lower container of FIG. 2. Whenthe pressure transfer fluid 27a is air, the ambient gas trapped incompartment 27 is pressurized when the container 20 is warmed to atemperature at which the propellant begins to vaporize. The valves 19and 25 of FIG. 2 are opened when the upper and lower containers 10 and20 are connected. The propellant 28a in propellant chamber 28 exertssufficient pressure on the compressed gas in compartment 27 to force theproduct 33 to be dispensed from the upper container 10. Pressure hasdefinite advantages over cooling since cooling takes a great deal oftime. Also, some products to be dispensed have temperature restrictionssuch that, to dispense the product, the container holding the propellantmust be warmed up to ambient temperature before it can be connected tothe container holding the product to be dispensed.

FIG. 5 illustrates an alternate embodiment wherein the product 33 to bedispensed is housed in a lower container 40 and the propellant 28a andpressure transfer fluid 27a are housed in an upper container 50. Thelower container 40 has side walls 41, lower wall 42 and an upper wall43, the upper wall including an opening therein around which is securedan annular, externally threaded projection 44. The upper container 50includes side walls 51, lower wall 52 and upper wall 53, the upper wallincluding a valve support member 54 clamped to the upper wall 53 andsupporting a valve 14 which controls product flow from dispensing nozzle15 by depression of the finger actuator 16. A dip tube 13 extendsdownwardly through a sealed opening 59 in the lower wall 52 of the uppercontainer 50. A valve may be included in the opening 59 so that thelower container 40 can be pressurized with a pressure transfer fluid27a. A flexible wall 60 is clamped at its lower end in the uppercontainer 50 where the side wall 51 and lower wall 52 intersect and atits upper end where the upper wall 53 and the valve support member 54intersect to separate upper container 50 into propellant chamber 61containing the propellant 28a and transfer fluid chamber 62 receivingthe transfer fluid 27a. If no valve is provided in opening 59 thepropellant 28a may be liquefied by cooling. Before the upper container50 is warmed appreciably it is connected to the lower container 40containing the product 33 to be dispensed, as illustrated in FIG. 5. Asthe upper container 50 warms and the propellant 28a vaporizes, it exertssufficient pressure on the air contained in upper transfer fluid chamber62 through the flexible wall 60, and the air exerts sufficient pressureon the product 33 to be dispensed in the lower container 40, to forcethe product 33 out through the dip tube 13 and dispensing nozzle 15 onopening of the valve 14 by depression of the finger actuator 16.

Flexible cellular material containing liquefiable propellant such as theone shown in FIG. 11 and described later may be substituted forpropellant chamber 61 and the flexible wall 60.

FIG. 6 illustrates an embodiment of the invention utilizing an integralcontainer 70 having an outer wall 71, an inner container 72, a top wall73 having a threaded opening therein and a lower wall 74 having a valvedopening 75 therein. The inner container 72 is secured to the top wall 73by suitable means. A threaded member 76 screws over the opening in thetop wall 73, the threaded member supporting a valve 14 which controlsflow of the product 33 to be dispensed from a flexible bag 30 throughnozzle 15 when the finger actuator 16 is depressed. The bag 30,containing the product 33 to be dispensed, is secured at its upper endaround the valve 14. An inner container 72 of the container has openings81 therein so that the pressure transfer fluid 27a in the chamber 82 isfree to flow into the space 83 surrounding the bag 30. Propellantchamber 84 formed by the inner container 72 and a flexible wall 85,secured at its upper end to the inner container 72, holds the propellant28a. A flexible cellular material holding the propellant may besubstituted for this propellant chamber 84. The pressure transfer fluid27a is injected into the container through valved opening 75 and exertssufficient pressure against the flexible wall 85 or cellular material toliquefy the propellant 28a contained in the propellant chamber 84. Thepressure transfer fluid 27a also exerts pressure against the flexiblebag 30 through openings 81. When the finger actuator 16 is depressed theproduct 33 is forced by substantially constant pressure through thevalve 14 out through dispensing nozzle 15. As the propellant 28a inpropellant chamber 84 vaporizes it exerts a continuous constant pressureagainst the pressure transfer fluid 27a in chamber 82 which, in turn,exerts pressure against the product 33 to be dispensed, resulting,ultimately, in discharge of substantially all of the product 33contained in the flexible bag 30.

FIG. 7 illustrates a further embodiment of this invention utilizing anintegral container 90 having an upper threaded opening 99 and a lowerwall 74 divided into an upper portion 91 and lower portion 92 by aforaminous barrier 93. The propellant 28a is contained in a flexiblecompartment 95 located in the lower portion 92 of the container 90. Theproduct 33 to be dispensed is held in a flexible bag 30 secured at itsupper end around a valved outlet 97. The valved outlet 97 is supportedby a threaded member 98 threadedly secured in the opening of container90. The lower wall 74 has a valved outlet 101 therein. A pressuretransfer fluid is injected under pressure into the chamber 102 to exertsufficient pressure against the flexible compartment 95 to liquefy asubstantial amount of a propellant 28a contained therein. Flexiblecellular material may be substituted for the flexible compartment 95.The pressure transfer fluid 27a exerts pressure against the flexible bag30 holding the product 33. When the finger actuator 16 is depressed toopen the valve in valved outlet 97 the product 33 is forced out throughthe valved outlet and dispensing nozzle 15. As the liquefied propellant28a in flexible compartment 95 vaporizes it exerts a continuous,substantially constant pressure against the pressure transfer fluid 27ain chamber 102 which, in turn exerts a continuous, substantiallyconstant pressure against the product 33 in flexible bag 30.

FIG. 9 illustrates one form of a coupling which may be used to connect asource of pressurized transfer fluid, such as water, with the containerdesigned to hold the pressure transfer fluid and propellant. The deviceconsists of a base 105, on one side of which is cut a female thread 106designed to connect with the threaded connector on the container and onthe other side of which is cut a male thread 107 designed to connectwith a conventional water faucet connection. In the embodiment shown thefemale thread 106 is adapted to be connected to the externally threadedprojection 24 of the lower container 20 of FIG. 2.

FIG. 8 illustrates a simple means of providing compressed air as apressure transfer fluid. Tubes 108 and 109 are secured, respectively, tothe openings 110 in the upper end and 111 in the lower end of container112. The lower tube 109 is connected to a source of water underpressure. The upper tube 108 is connected to the valved outlet of, forexample, the lower container 20 illustrated in FIG. 2. When water entersthe container 112 the air above the level of the water is compressed andforced out through tube 108 under pressure into the transfer fluidcompartment 27 of the lower container 20.

With the pressurized dispensers disclosed there is no discharge ofpropellant into the atmosphere. The propellant containers, such as thelower container 20 of FIG. 2, can be reused repeatedly.

FIG. 10 illustrates a further embodiment of this invention similar toFIG. 7 except on a larger scale and for a different end use, such asdispensing paint. The side walls 113 of the integral container areenclosed by an upper wall 114 and a lower wall 115. The container isdivided by a foraminous wall 93 into an upper portion 91 and lowerportion 92. The propellant 28a is contained in a flexible compartment 95located in the lower portion 92 of the container. Flexible cellularmaterial may be substituted for the flexible compartment 95. The product33 to be dispensed is also held in a flexible bag 117 secured at itsupper end around the periphery of and between the upper wall 114 and theside wall 113 by means of "O" ring 129 or other suitable sealing meansand by means of bolts 120 or other suitable fastening means. The outlet119 for the product 33 to be dispensed is located on top of the upperwall 114. The lower wall 115 is secured and sealed to side wall 113 bywelding or other suitable means and the foraminous wall 93 is secured tothe side wall 113 of the container by means of screws and anchor plates130 as illustrated. The foraminous wall 93, however, may be securedpermanently to the side walls 113 of the container and the lower wall115 secured by similar means as the top wall 114. Casters 126 may beprovided on the bottom of the container for easy handling during thedispensing of the product 33. An extension hose 121 is secured to theoutlet 119. A flow regulator-stop valve 122 is provided toward the endof the extension hose 121 to which a spray gun or paint roller 123 oranother device is connected. A pressure transfer fluid 27a, such aswater, is injected under pressure through valve 124, located at thebottom of the upper portion 91 of the container, into the chamber 102.The pressure transfer fluid 27a exerts sufficient pressure against theflexible compartment 95 to liquefy a substantial amount of thepropellant 28a contained therein. The pressure transfer fluid 27a alsoexerts pressure against the flexible bag 117 holding the product 33.When valve 122 is opened, the product is forced out through the hose 121to the spray gun or paint roller 123, or other devices attached.

The method of dispensing products using the systems illustrated in FIG.11 differs from that described in U.S. Pat. No. 3,659,395 in that aliquefiable propellant or blend of liquefiable propellants incombination with a non-liquefiable gas are sealed within the foam.

FIG. 11 illustrates a modified form of the power unit which does notutilize a pressure transfer fluid as described with respect to theembodiments of FIGS. 1 to 7 and 10. FIG. 11 illustrates a containerwhich may be made of glass or metal or any other suitable material. Theside walls 131 of the container are enclosed by a top wall 132 and abottom wall 133 which are secured around the side walls of the containerin such a way that the container will withstand internal pressure.Suitable fastening means for fastening the top and bottom walls to theside walls are known and obvious to those skilled in the art. The topwall of the container is fitted with a dispensing nozzle 15 and fingeractuator 16.

The liquefiable propellant, blend thereof or mixture of a liquefiablepropellant and non-liquefiable gas is enclosed within a flexible member135 which holds the propellant and is preferably impermeable thereto andwhich is compatible with the product to be dispensed. As illustrated inFIG. 11 the flexible member 135 is in a collapsed or near collapsedstate due to the presence of the product to be dispensed in thecontainer. The flexible member 135 may be made of a resilientmulti-cellular foam material such as polyurethane, polyvinyl chloride,or polyethylene holding the liquefied the propellant in the individualcells. The foam material may be either a closed cell or open cell foamalthough a closed cell foam is preferred. Around the foam material 135is a resilient covering 136 which is of a material substantiallyimpermeable to the propellant used in and is compatible with the productto be dispensed. The lining or cover 136 may also be an integral skinlayer formed during making of the flexible member foam material 135. Asthe product is dispensed the liquefied propellant in the cells of themulticelular material vaporizes and expands the foam material to forcethe product to be dispensed from the container.

A preferred method of making a pressurized dispenser of the typeillustrated in FIG. 11 is to form the foam member 135 in situ byinjecting an uncured polymer from which the foam is to be made, acatalyst for the polymer, a liquefiable propellant which may also serveas the foaming or blowing agent along with a non-liquefiable gas,inhibitors, surfactants, etc. into the container under pressure throughan opening in the container wall. As the blowing agent vaporizes itdevelops cells in the mass of polymerizable foam and expands the polymersimultaneously with cure or crosslinking thereof to fill the interior ofthe container. The interior of the container, prior to injection of thefoam, should be coated with a release agent such as a polyethylene film,a metal stearate or other conventional release agent. A lining 136 forthe foam material should also be included unless the foam material isformed to have its own integral, surface skin or the foam is made ofimpermeable closed cells. The production of cellular plastic foams usingphysical foaming agents which are also liquefiable propellants is wellknown. Reference may be made, for example, to Modern PlasticsEncyclopedia Vol. 50: No. 10A (October 1973) pp. 127-134 for adescription of physical blowing agents and their use in the manufactureof plastic foams. Reference can also be made to pp. 134-137, 138-143 and148-150 for a description of processes for making flexible elastomericintegral skin urethane foams, polyethylene foams and vinal foams.

After the foam has set in the container the product to be dispensed isinjected into the container under pressure through the dispensing nozzleor other opening in the container to release the foam from the containerwalls and to collapse the foam and liquefy the propellant contained inthe cells of the foam material 135. Thereafter, the foam material 135exerts pressure on the product to be dispensed sufficiently to force theproduct from the container on depression of the finger actuator of thecontainer.

Rather than forming the foam in situ in the container the foam may beformed under pressure outside of the container and then inserted intothe container under pressure. Likewise, the formed foam can be cooledsufficiently to liquefy the liquefiable propellant or blowing agent inthe cells and the cooled foam then inserted into the container. Witheither of the two previously mentioned alternatives, the top or bottomwall of the container would not be secured to the container until thefoam member 135 is inserted therein.

A similar process may be used in making accumulators of the typeillustrated in FIG. 12 wherein a foam material is used in lieu of theflexible bag 144. The foam material may be foamed in situ in the housing141 or foamed outside the housing and inserted in the housing aspreviously described with reference to FIG. 11.

With regard to the embodiment illustrated in FIG. 11 the flexible member135 or flexible bag is charged with a mixture of a liquefiablepropellant or blend thereof and a non-liquefiable gas in a volume ratiothat depends on the particular application.

In all instances referred to with respect to FIGS. 1-7, 10 and 11 theflexible bag holding the propellant or the material to be dispensedwhich is in contact with the propellant should be made of material thatis fairly impermeable to the propellant used and which is compatiblewith the propellant and with the product to be dispensed. The flexiblebag or foam material holding the propellant should be able to expand toapproximately the full volume of the interior of the container in orderto force the product to be dispensed from the container completely. Ifthe bag is made of non-resilient but flexible material such aspolyethylene and the bag is filled with liquefied propellant andcollapsed to a crumpled form by the product to be dispensed or pressuretransfer fluid, it leaves most of the container unfilled. As theliquefied propellant vaporizes the flexible bag expands until it againapproximately fills the container. The flexible bag may also be made ofa rubbery, resilient or elastic material such as a natural or syntheticrubber which can shrink or expand according to the pressure exerted bythe propellant. Suitable materials for holding the propellant or theproduct to be dispensed in contact with the propellant include syntheticrubber such as buna-N, Neoprene, butyl rubber, polybutadiene, ABSpolymers, styrene-butadiene rubbers, the various acrylonitrile rubbers,natural rubbers and other flexible materials such as vinyl chloride,polyurethane, polyethylene, polypropylene, nylon and similar materials.In practicing the invention with the embodiments illustrated in FIGS. 1to 11 with regard to dispensers, it is necessary to select a propellantwhich has a boiling point or blend of propellants which have a boilingpoint range below the temperature at which the reuseable container is tobe used. The boiling point or range of the propellant or blend ofpropellants should not be so low that the propellant cannot be liquefiedconveniently when recharging the container by use of a pressure transferliquid for the product to be dispensed or in some instances by cooling.Generally, the boiling point of the propellant or blend of propellantsshould be higher than -45° F. and preferably between -25° F. and 50° F.Monochlorodifluoroethane sold under the trademark "Freon" 142b issuitable as one of the propellants either alone or blended with otherpropellants such as "Freon" 12, "Freon" 21, "F-114", etc. Rather thanthe fluorocarbon propellants, the various embodiments described may usean aliphatic hydrocarbon propellant such as propane, isobutane,n-butane, pentane or mixtures thereof chlorinated hydrocarbonpropellants such as ethyl chloride, methyl chloride and methylenechloride cyclic organic compounds, nitrogen compounds and unsaturatedorganic compounds. Such propellants for dispensing products preferablyshould be conveniently liquefiable by a charging pressure of from 5 to100 psig at a temperature of 32° to 100° F., or by cooling at atemperature of between 32° F. and 50° F. The propellant may be blendedwith a non-liquefiable gas at the normal use temperature range of thecontainers. Such gases may include nitrogen, helium, argon, carbondioxide and other gases of a similar nature which are not liquefiable atthe pressures and/or temperature normally encountered. One reason forblending a non-liquefiable gas with the liquefiable propellant is toprevent cracking of the flexible wall of the container. When thecontainer is to be reused, the flexible wall must be capable of beingcollapsed and expanded repeatedly without developing cracks or leaks.The non-liquefiable gases blended with the liquefiable gases preventcollapse of the bag beyond a certain point and thus prevent sharpcreases from being formed in the flexible bag which may develop cracksand leaks over a period of time.

The above temperature and pressure ranges for suitable liquefiablepropellants are given for those consumer applications where tap waterand/or refrigerators are the principal means of liquefying thepropellants. For commercial and industrial applications, the pressureranges would be much higher for high pressure systems.

In the embodiments illustrated in FIGS. 1-7, 10, 11 and 12, the flexiblebag containing the propellant or blend of propellants with or withoutthe non-liquefiable gas may be a flexible, multi-cellular material suchas a multi-cellular foam wherein the liquefiable propellant is entrappedwithin the cells. The cells may be of open or closed type but preferablyof the closed type. The cell wall is preferably impermeable to thepropellant. If necessary, a lining or integral skin may cover theexterior of the foam material to contain the propellant.

For fluid reservoir systems there is no limit on the propellant pressureas long as suitable liquefiable propellants can be found. The pressurerange is generally much higher than those used in the product dispensingsystems.

The containers described in FIGS. 1-7, 10 and 11 can be used as a meansof dispensing a multitude of liquid and/or semi-liquid products such asinsecticides, herbicides, fertilizers, air fresheners, window washingcompositions, oil and latex paints, perfumes, etc. The systems can alsobe used to supply water under pressure for portable showers or fordrinking water for boats and recreational vehicles.

A further use of the concept described in the application is illustratedin FIG. 12 illustrating a pneumatic or hydraulic fluid system. Unitswhich are structurally identical to FIG. 12 are manufactured by GreerHydraulics, Inc. and are used as bladder accumulators. Bladderaccumulators are used in hydraulic or pneumatic fluid systems as linkagecompensators, thermal expansion compensators, fluid make-up devices,pulsation dampeners, hydraulic shock absorbers, holding devices,transfer barriers, fluid dispensers, etc. Referring to FIG. 12, theaccumulator is inserted in a hydraulic or pneumatic line 140. The unitincludes a shell 141 of metal or other suitable material having a fluidport 142 at one end thereof communicating through a suitable T fitting143 with the hydraulic or pneumatic line 140. A flexible bladder 144 ispermanently sealed and/or attached around the upper edge of the upperportion of the shell by conventional means known in the art.Communication with the bladder is through a valve 145. The bladdergenerally known to the art is charged with a non-liquefiable gas such asnitrogen, argon, helium, etc. to a pressure determined by the workingpessures and loads handled by the fluid or pneumatic system. When usedas a shock absorber, the bladder senses the shock pressure generated bythe fluid system and absorbs it. A flexible cellular material asdescribed in FIG. 11 may be used in lieu of the flexible bladder 144 inFIG. 12. One disadvantage of the accumulators which employ anon-liquefiable gas in the bladder is that the pressure-volume relationis not constant with pressure changes in the system.

In the embodiment illustrated in FIG. 12 the bladder is charged with aliquefiable propellant gas or a blend of liquefiable propellant gasesand a non-liquefiable gas. The advantage of using a liquefiablepropellant gas which is liquefiable at the pressures and temperatureswhich will be encountered by the unit in service will insure that thepressure of the system remains constant even though the fluid in thesystem is subjected to sudden shocks. If the pressure of the fluidsystem increases, liquefaction of a portion of the liquefiable gas inthe bladder will occur sufficient to maintain the pressure of the fluidsystem substantially constant. This is illustrated by the comparativegraphs of FIGS. 13 and 14. One advantage of such a unit, when used as apulsation dampener or hydraulic shock absorber, is that mechanical shockoccurs with less potential damage occurring to the system or machinery.Liquefiable gases which may be used include fluorocarbons, hydrocarbonsand other liquefiable propellants described previously with regard toother embodiments.

I claim:
 1. A pressurized dispenser for dispensing a liquid orsemi-solid product without release of the propellant dispensing theproduct to the surrounding environment, comprising:container meanshaving a valved opening holding a product to be dispensed, a flexiblewall in the container means forming a sealed compartment holding acompressible and liquefiable propellant therein liquefiable under theinfluence of temperature, pressure or both, out of contact with theproduct to be dispensed, and means for introducing a transfer fluidunder pressure into the container means, the transfer fluid in contactwith the flexible wall of the compartment holding the liquefiablepropellant and with the product to be dispensed, the liquefiablepropellant exerting sufficient pressure on the product to be dispensedthrough the transfer fluid to force the product out of the containermeans through the valved opening when the valve is opened, wherein thecontainer means includes a first container including the valved openingholding the product to be dispensed separate from a second containeradapted to be used with the first container holding the transfer fluidand the liquefiable propellant.
 2. The dispenser of claim 1 wherein themeans for introducing the transfer fluid includes an opening in theflexible wall of the sealed compartment in the second container forreceiving and holding an inert gaseous transfer fluid, wherein the firstcontainer includes means for connecting the opening of the secondcontainer to the first container to allow the gaseous transfer fluid toenter the first container and exert sufficient pressure to dispense theproduct from the first container.
 3. The dispenser of claim 2 whereinthe means for connecting the opening of the second container to thefirst container includes valved connector means connecting to theopening of the second container.
 4. The dispenser of claim 3 wherein thefirst container includes a first tube extending from the valved openingfor conveying the product to be dispensed out of the first container anda second tube extending from the valved connector means for conveyingthe gaseous transfer fluid into the first container from the secondcontainer to force the product therefrom.
 5. The dispenser of claim 1wherein the transfer fluid is water.
 6. The dispenser of claim 1 whereinthe transfer fluid is a non-hydrocarbon, non-fluorocarbon gas which isnot liquefiable at the use pressures and/or temperatures of thedispenser.
 7. The dispenser of claim 1 wherein the compressible andliquefiable propellant is selected from the group consisting of aliquefiable propellant, a blend of liquefiable propellants, and amixture of a liquefiable propellant or blend thereof and a gas which isnon-liquefiable under the pressure and temperature conditions to whichthe dispenser will likely by subjected.
 8. The dispenser of claim 1wherein the transfer fluid is contained in the space between the wall ofthe second container and the flexible wall of the sealed compartment andwherein the means for introducing the transfer fluid into the secondcontainer is a valved opening.